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Using the Guider
In the dome: To use the guider, you'll have to use the QSI CCD on the back of the finder scope. Make sure it is plugged in (there should be a power cord and a data cord). There is also a MicroTouch focuser associated with this scope. Make sure a telephone-like cord is plugged into it. Finally, there is the MicroTouch control box in the dome, attached to the telescope pier. Make sure it is plugged in, with both a power cord and a data cord. Camera 1 = Apogee Alta on the 24 inch. Camera 2 = QSI CCD on the guider scope. The QSI CCD should appear as Camera 2 in Maxim DL. Cool it down by going to the Setup tab in the Camera Control Window, and hit the Coolers On button. Take images with both Camera 1 and Camera 2, by toggling the selected button under the Expose tab in the Camera Control window. Make sure the images from the two CCDs are aligned in the same way, with North upward and East to the left. You can check against SIMBAD to make sure the alignment matches. Focus Camera 2 by clicking on the Feather icon ('MicroTouch Controller') on the desktop of the 'Camera' computer. In the Microtouch Controller window, click Connect. To change the focus value, just type in a new number under 'Target Position' and hit GOTO. You might find that the focus is really far off from true, particularly after a public night. When stars are really out of focus, they'll look like faint blurry circles. When they are getting more in focus, they'll start to have compact cores but still fuzzy halos around them. Jogs of 500 focus points are probably good for honing in on a focus value coarsely. Steps of 100 are good for fine changes. Last time we settled on a focus value of 37,250. Once you are happy with how the image looks coming off Camera 2, we can start guiding! In the Camera Control window, select the Guide tab. Make sure Camera 2 is selected. Select Expose, and take a 3--5 second long exposure. In ACE, go to Instruments > Auto Guider Display. A gain of something like 0.1 is good. Click the ON bubble under Autoguider to turn on the connection to the guider. Back in Maxim DL, open the View > Zoom Window. Find a star that is nice and easy to see in the 3--5s exposure. Center this star in the zoom window and click on it. Then start tracking by clicking Track rather than 'Expose' in Maxim DL. The exposure you have set under 'Seconds' will be how often the CCD reads out. It will read out a little window (~20x20 pixels) centered on your star. You want your star to sit in the middle of that box and stay there. Maxim DL is measuring the position of the star and updating it when it is listing new values of xerr and yerr. These values should also be reflected by changes under 'Corrections' in the Auto Guider window of ACE. Whenever you move the telescope with ACE, Auto Guider in ACE will be turned off, and you'll have to go through the whole process of finding a guide star again. Annoying bug/feature: If the star fades (i.e., because of clouds), Maxim DL won't tell ACE that the corrections should be zero. It will instead maintain the last correction and guide the source away from the field center. So if your star fades, turn off guiding promptly. You can check to see how the guider corrections are doing by clicking on Graph in the Camera Control > Guide window. The differences in X and Y should converge to zero. If the guider corrections seem to keep overshooting zero, the gain might be set too large. If one of the X or Y directions is bouncing around more than the other, you can go into Settings in the Camera Control > Guide window, and make the bouncier dimension a slightly lower speed (say y = -0.7). In the Settings tab: speeds should be set roughly to xspeed=1, yspeed = -1. Yspeed has to be negative for the guider to correct in the right declination direction! You can leave the aggressiveness at its default value, 8. Make sure Pier Flip is selected otherwise the movements will be in the wrong direction.